Increasing the overall power of a single solid state power amplifier requires increases in the device size and current at any voltage. Increasing the device size and current can lead to corresponding impedance matching problems. The impedance matching issue has lead to designs involving power combining of one form or another, such as for example combining power from multiple smaller devices. There is also a need to allow power amplifiers to self calibrate using low overhead in circuitry, and minimal degradation of power consumption and performance. Current systems using multiple power amplifiers require complex and time consuming post fabrication trimming and component selection for optimal gain, power output, and stability that add to cost and complexity of the packaging and fielding of amplifier modules.
Additionally, ordinary RF amplifiers introduce distortions to amplitude and phase information associated with digital modulation methods. The distortion arises from gain compression and phase changes in the amplifier as the envelope moves through different power levels. The distortion can be avoided by operating the amplifier far below its peak rated power where gain compression and phase change are lower. Many transmitters handling high order digital data with both amplitude and phase modulation operate with amplifiers that are backed off from peak power, having sufficient linearity to avoid distortion of the amplitude and phase information. This results in the need for a much larger amplifier operating at lower direct current (DC) to RF efficiency. As a result of these deficiencies, there is a need for a high efficiency power amplifier capable of extremely high frequency operation, on the order of about 40 GHz to about 220 GHz or higher operating frequencies, and that is directly coupled to an antenna array that is adapted to transmit digital data using standard high order modulation schemes.